Verify that user classes do not extend any of Bool, Double, ObjectArray,

runtime/vm/class_finalizer.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/longjump.h"
@@ skipping 245 matching lines @@
   cls.set_super_type(super_type);
   const Class& super_class = Class::Handle(super_type.type_class());
   if (cls.is_interface() != super_class.is_interface()) {
     String& class_name = String::Handle(cls.Name());
     String& super_class_name = String::Handle(super_class.Name());
     ReportError("class '%s' and superclass '%s' are not "
                 "both classes or both interfaces.\n",
                 class_name.ToCString(),
                 super_class_name.ToCString());
   }
+  // If cls belongs to core lib or to core lib's implementation, restrictions
+  // about allowed interfaces are lifted.
+  if ((cls.library() != Library::CoreLibrary()) &&
+      (cls.library() != Library::CoreImplLibrary())) {
+    // Prevent extending core implementation classes Bool, Double, ObjectArray,
+    // ImmutableArray, GrowableObjectArray, IntegerImplementation, Smi, Mint,
+    // BigInt, OneByteString, TwoByteString, FourByteString.
+    ObjectStore* object_store = Isolate::Current()->object_store();
+    const Library& core_impl_lib = Library::Handle(Library::CoreImplLibrary());
+    const String& integer_implementation_name =
+        String::Handle(String::NewSymbol("IntegerImplementation"));
+    const Class& integer_implementation_class =
+        Class::Handle(core_impl_lib.LookupClass(integer_implementation_name));
+    const String& growable_object_array_name =
+        String::Handle(String::NewSymbol("GrowableObjectArray"));
+    const Class& growable_object_array_class =
+        Class::Handle(core_impl_lib.LookupClass(growable_object_array_name));
+    if ((super_class.raw() == object_store->bool_class()) ||
+        (super_class.raw() == object_store->double_class()) ||
+        (super_class.raw() == object_store->array_class()) ||
+        (super_class.raw() == object_store->immutable_array_class()) ||
+        (super_class.raw() == growable_object_array_class.raw()) ||
+        (super_class.raw() == integer_implementation_class.raw()) ||
+        (super_class.raw() == object_store->smi_class()) ||
+        (super_class.raw() == object_store->mint_class()) ||
+        (super_class.raw() == object_store->bigint_class()) ||
+        (super_class.raw() == object_store->one_byte_string_class()) ||
+        (super_class.raw() == object_store->two_byte_string_class()) ||
+        (super_class.raw() == object_store->four_byte_string_class())) {
+      ReportError("'%s' is not allowed to extend '%s'\n",
+                  String::Handle(cls.Name()).ToCString(),
+                  String::Handle(super_class.Name()).ToCString());
+    }
+  }
   return;
 }
 
 
 void ClassFinalizer::ResolveDefaultClass(const Class& interface) {
   ASSERT(interface.is_interface());
   if (interface.is_finalized()) {
     return;
   }
   Type& factory_type = Type::Handle(interface.factory_type());
@@ skipping 759 matching lines @@
   ASSERT(msg_buffer != NULL);
   va_list args;
   va_start(args, format);
   OS::VSNPrint(msg_buffer, kBufferLength, format, args);
   va_end(args);
   isolate->long_jump_base()->Jump(1, msg_buffer);
   UNREACHABLE();
 }
 
 }  // namespace dart